Bunk bed



FIG. 1 is a perspective view of a bunk bed, showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left-side elevational view thereof, the right-side elevational view being a mirror image thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a bottom plan view thereof.

The broken lines showing a graphic pattern applied to the design in FIG. 1 depict environmental matter and form no part of the claimed design. 

I claim the ornamental design for a bunk bed, as shown and described. 